Home Casting const void* const to const char* const produces the "ignored-qualifiers" warning, why?

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Casting const void* const to const char* const produces the "ignored-qualifiers" warning, why?

March 9, 2023

I don’t understand why the following code gives the "type qualifiers ignored on cast result type" warning in GCC, can you please explain?

#include <stdint.h>

char f(const void* const a) noexcept {
    return static_cast<char>(*static_cast<const char* const>(a));
}

https://godbolt.org/z/n8Ws9aTcq

>Solution :

A non-class non-array prvalue cannot be cv-qualified.

This means that your static_cast<const char* const>(a) is exactly the same as static_cast<const char*>(a), the pointer itself isn’t const-qualified. It’s simply discarded, which is what the warning is telling you about (the second const is what is being ignored)